This invention relates generally as indicated to a fiber optic light emitting panel and method of making same, and more particularly to a light emitting panel including an emitter surface in which optical fibers are woven into a sheet or mat and coated with a material having a refractive index that will cause a change in the attenuation of the optical fibers in the emitter surface to increase the optical efficiency of the panel.
It is generally known to weave optical fibers into a panel or the like and make the panel luminous in one or more selected areas by frustrating the total internal reflection character of the optical fibers in such areas. Illumination in these areas is caused by allowing light which is transmitted to the woven optical fibers through a cable or light pipe from a remote light source to emerge from the optical fibers in the selected areas.
Normally the light entering from one end of an optical fiber passes out the other end thereof after a certain amount of loss takes place. However, if the surface of the optical fiber is disrupted as by scratching or otherwise deformed as by bending the optical fiber at a plurality of discrete locations along its length such that the angle of bend approximately exceeds the angle of internal reflection, light will be emitted at these locations.
One of the primary advantages of constructing a light emitting panel utilizing such optical fibers is that the light source can be located remote from the panel for ease of changeability. Also, because the light source need not be incorporated in the panel itself, the panel can be made quite thin and of almost any size and shape, making it especially suitable for use in the back lighting of liquid crystal materials as well as signs and control panels generally.
However, there is a continuing need to improve the uniformity and efficiency of the light emitted by such fiber optic panels. Also, there is a limit to the amount of light that can be emitted along the length of each fiber. The light that is not emitted is trapped in the fiber and becomes wasted energy. Accordingly, it would be desirable to increase the amount of light that can be emitted from each fiber in order to increase the efficiency of the panel.